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Halton Hills - Impact Assessment Results

The TPAP includes extensive studies to identify the potential environmental impacts associated with potential new infrastructure, including the construction and operation of proposed electrified service. We have started these studies and want to provide you an update on the status for your community.

Potential effects on terrestrial features, wildlife/wildlife habitat, species at risk, watercourses, aquatic habitat were assessed.


Four butternut trees (Species at Risk) were identified within 50 metres of the Georgetown Switching Station.

  1. A Butternut Health Assessment will confirm whether the tree is a pure butternut or a hybrid and compensation will be determined based on this assessment.

Several Significant Wildlife Habitats (SWH) may be affected by the implementation and operation of the OCS infrastructure and bridge/rail overpass modifications.

  1. Implement measures to avoid harming, injuring or interfering with existing species, its residence and/or its habitat.
  2. During breeding season, if bridge/rail overpass modifications are proposed to take place, checks for protected birds (as per the Migratory Birds Convention Act) or Barn Swallow nests will take place prior to start of construction.

Potential impacts to wetlands and waterbodies resulting from erosion and sedimentation from construction.

  1. Construction activities will maintain buffers established during the design phase to minimize potential impacts.

Potential effects on land use and socio-economic features due to the construction and implementation / long-term operation of the physical project components were assessed.


Nuisance (noise/vibration and visual) effects for adjacent sensitive receptors (i.e., religious institutions, schools, child care centres, etc.), residential areas, parks and trails.

  • Potential noise and visual effects are anticipated to be temporary in nature and will be minimized based on the implementation of mitigation measures.
  • We have a dedicated Community Relations team available at any time to answer questions and notify residents/businesses/property owners of construction works, including night work.

Potential effects on existing view sheds caused by the proposed new infrastructure (OCS, TPFs, bridge modifications) were assessed.

Areas of Potential Moderate Visual Impact:

Areas of potential moderate visual impact can include residential areas where homes are more than right eight metres from the tracks and areas where existing vegetation provides a screen from the infrastructure.

  1. Moderate impacts on the north side of the SWS site are anticipated
  2. Lands bordering Emmerson Park in Georgetown
  3. Residential homes located south of Side Road 22
  4. Areas where the Bruce Trail runs parallel with the rail corridor
  5. At the 3rd Line level crossing, where the Guelph Radial Line Trail runs parallel to the rail corridor
  6. Areas bordering Sir Donald Mann Park in Acton


  • Screening measures for the SWS site could include: fencing and/or structured wall landscaping, and/or building enclosure.
  • Erecting construction hoarding fence to screen construction activities.
  • Placing tarps over exposed excavations.

EMFs are invisible forces that surround electrical equipment, power cords and power lines. You cannot see or feel EMFs.

On a daily basis, we are exposed to electric and magnetic fields (EMFs) generated by household wiring, lighting, and electrical appliances.
Every time you use electricity and electrical appliances, you are exposed to EMFs at extremely low frequencies.
EMFs are strongest when closest to the source. As you move away from the source, the strength of the fields fades rapidly.


  1. Further testing and verification will be carried out during the detailed design phase once the rolling stock is established.
  2. Confirm background EMF/EMI measurements during detailed design.
  3. Implement an Electromagnetic Compatibility (EM Control Plan.
  4. Identify, and implement, grounding and shielding measures.

A comprehensive summary of Cultural Heritage Resources (CHRs) within the study area was established; potential effects on CHRs, mitigation measures and/or recommendations for further study were assessed.

The 22nd Side Road overpass bridge may require additional clearance levels for the new infrastructure.


  1. The track may be lowered by approximately 0.376 m or 14.8“ to accommodate the OCS infrastructure and sub-ballast of the tracks.
  2. A Cultural Heritage Evaluation Report (CHER) for the 22nd Side Road Bridge was undertaken and determined that the bridge does not have provincial interest or value.

A Stage 1 Archaeological Assessment (AA) was completed that assessed the study area for potential archaeological resources. The Stage 1 AA study included a history of Indigenous and Euro-Canadian land use, known and previously registered archaeological sites, and previous archaeological assessments.

The corridor includes lands that retain archaeological potential in the area of the Georgetown SWS site.


  1. A Stage 2 Archaeological Assessment is required prior to any construction impacts within the Georgetown SWS study area.
  2. Should previously undocumented archaeological resources be discovered, they may be a new archaeological site and therefore subject to Section 48 (1) of the Ontario Heritage Act. The person discovering the archaeological resources must cease alteration of the site immediately and engage a licensed consultant archaeologist to carry out archaeological fieldwork.

Properties within the Study Area were assessed for the potential presence of soil and/or groundwater contamination.

Construction could expose contaminated materials and/or result in the spreading of contaminated materials.
Construction could expose groundwater and associated contamination.
Exposure to contaminated materials/groundwater can put below grade construction workers health and safety at risk.


  1. Conduct Phase II Environmental Site Assessment for soil and groundwater contamination where excavations are planned, during detailed design.
  2. Develop a Soil and Excavated Materials Management Plan (during detailed design) for the handling, management, and disposal of all excavated material that is generated or encountered during the works.
  3. Develop a Groundwater Management Plan (during detailed design) to guide the handling, management, and disposal of groundwater encountered during the works.

An assessment of the potential effects of the proposed infrastructure on water supply wells, groundwater dependent ecological features, etc. was completed.


The proposed infrastructure is expected to change groundwater flow and impact recharge capabilities along the segment. General construction activities have the potential to affect groundwater and/or surface water quality through minor contaminant releases.

Operations and Maintenance:

Reduction in groundwater infiltration due to construction of impervious surfaces, soil compaction, use of finer grained materials.


  1. Prepare a Groundwater Management Plan that will evaluate potential groundwater discharge options prior to construction.
  2. Prepare and implement a Spill Prevention and Response Plan prior to construction.
  3. Negligible change to groundwater infiltration is anticipated due to the limited area that is to be covered by the proposed project components and the permeable materials typically utilized.

A preliminary assessment of drainage patterns, drainage features, potential outfall, footprint areas for future building and equipment areas, and runoff was undertaken as part of the TPAP.

The proposed works may result in increases to impervious areas, with potential effects to water quantity and quality.
There may be alterations to the local drainage system, both overland (major drainage system) and storm sewers (minor drainage system).
The proposed construction activities pose a potential impact due to sediment transport into adjacent natural areas


  1. Prepare a Drainage and Stormwater Report and an Erosion and Sediment Control Plan during detailed design.
  2. Assess the receiving capacity of the minor and major drainage systems during detailed design.
  3. Assess stormwater quality measures to provide a minimum 80% Total Suspended Solids (TSS) removal as per provincial guidelines.

We are conducting a noise and vibration impact assessment that will look at:

a qualitative assessment of the noise effects resulting from the change in diesel to electric propulsion along the Guelph Subdivision
an assessment of construction noise impacts, including mobile and stationary noise and vibration sources and recommended mitigation measures to be implemented and followed during the construction phase.


  1. With respect to mitigation, Metrolinx follows the 1995 MOEE/GO Transit Draft Protocol for Noise and Vibration Assessment and implements mitigation accordingly.
  2. When possible, construction will be limited to the time periods allowed by the locally applicable bylaws.
  3. All equipment will be properly maintained to limit noise emissions.

An air quality impact assessment is also underway, the scope will assess:

local air quality impacts associated with future operations of the electrified GO Rail Network
regional air quality impacts associated with future operations of the electrified Guelph Subdivision
local air quality impacts associated with construction activities


  1. The results of this air quality study, as well as mitigation recommendations, will be made available as part of future consultation.

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